1. Field of the Invention
The present invention relates to a display device and a method for producing the same. In particular, the present invention relates to a display device and a method for producing the same to be preferably used for producing a large screen display device by arranging a large number of display components having an optical waveguide plate for introducing light from a light source thereinto.
2. Description of the Related Art
Those hitherto known as the display device include, for example, cathode ray tubes (CRT) and liquid crystal display devices.
Those known as the cathode ray tube include, for example, ordinary television receivers and monitor units for computers. Although the cathode ray tube has a bright screen, it consumes a large amount of electric power. Further, the cathode ray tube involves a problem such that the depth of the entire display device is large as compared with the size of the screen.
On the other hand, the liquid crystal display device is advantageous in that the entire device can be miniaturized, and the display device consumes a small amount of electric power. However, the liquid crystal display device involves problems in that it is inferior in brightness of the screen, and the field angle of the screen is narrow.
In the case of the cathode ray tube and the liquid crystal display device, it is necessary for a color screen to use a number of picture elements (image pixels) which is three times a number of picture elements used in a black-and-white screen. For this reason, other problems occur, for example, the device itself is complicated, a great deal of electric power is consumed, and it is inevitable to cause the increase in cost.
In order to solve the problems described above, the present applicant has suggested a novel display device (see, for example, Japanese Laid-Open Patent Publication No. 7-287176). As shown in FIG. 56, this display device includes actuator elements 400 arranged for respective picture elements. Each of the actuator elements 400 comprises a main actuator element 408 including a piezoelectric/electrostrictive layer 402 and an upper electrode 404 and a lower electrode 406 formed on upper and lower surfaces of the piezoelectric/electrostrictive layer 402 respectively, and a substrate 414 including a vibrating section 410 and a fixed section 412 disposed under the main actuator element 408. The lower electrode 406 of the main actuator element 408 contacts with the vibrating section 410. The main actuator element 408 is supported by the vibrating section 410.
The substrate 414 is composed of ceramics in which the vibrating section 410 and the fixed section 412 are integrated into one unit. A recess 416 is formed in the substrate 414 so that the vibrating section 410 is thin-walled.
A displacement-transmitting section 420 for obtaining a predetermined size of contact area with respect to an optical waveguide plate 418 is connected to the upper electrode 404 of the main actuator element 408. In the illustrative display device shown in FIG. 56, the displacement-transmitting section 420 is arranged such that it is located closely near to the optical waveguide plate 418 in the OFF selection state or the unselection state in which the actuator element 400 stands still, while it contacts with the optical waveguide plate 418 in the ON selection state at a distance of not more than the wavelength of the light.
The light 422 is introduced, for example, from a lateral end of the optical waveguide plate 418. In this arrangement, all of the light 422 is totally reflected at the inside of the optical waveguide plate 418 without being transmitted through front and back surfaces thereof by controlling the magnitude of the refractive index of the optical waveguide plate 418. In this state, a voltage signal corresponding to an attribute of an image signal is selectively applied to the actuator element 400 by the aid of the upper electrode 404 and the lower electrode 406 so that the actuator element 400 is allowed to make a variety of displacement actions in conformity with the ON selection, the OFF selection, and the unselection. Thus, the displacement-transmitting section 420 is controlled for its contact and separation with respect to the optical waveguide plate 418. Accordingly, the scattered light (leakage light) 424 is controlled at a predetermined portion of the optical waveguide plate 418, and a picture image corresponding to the image signal is displayed on the optical waveguide plate 418.
When a color picture is displayed by using the display component, the following operation is performed. That is, for example, light sources for the three primary colors are switched to control the light emission time for the three primary colors, while synchronizing the contact time between the optical waveguide plate and the displacement-transmitting section with the cycle of color development. Alternatively, the contact time between the optical waveguide plate and the displacement-transmitting section is controlled, while synchronizing the light emission time for the three primary colors with the color development cycle.
Therefore, the illustrative display component suggested by the present applicant is advantageous in that it is unnecessary to increase the number of picture elements as compared with the black-and-white screen, even when the display device is applied to the color display system.
A large number of techniques have been hitherto suggested and practically used in order to produce a large screen display component by arranging a large number of display components (see, for example, Japanese Utility Model Publication No. 4-53675 and Japanese Laid-Open Patent Publication No. 8-17086).
However, when the large screen display device is produced by arranging a large number of display components having the optical waveguide plate as described above, the following problem arises. That is, if the display components are merely assembled with an adhesive or the like, then the light leaks at a boundary portion (juncture portion) of the optical waveguide plate, and the juncture portion is conspicuous.
It is also necessary that the design is made while considering such a feature that any disabled display component can be easily replaced with a new one.
Further, when a large screen display device is installed in a variety of districts, the production cost is effectively reduced if constitutive parts are transported to a working site, and the large screen display device is successfully assembled at the working site, as compared with a case in which the large screen display device is assembled in a factory, and it is transported therefrom.
The present invention has been made taking the foregoing problems into consideration, an object of which is to provide a display device and a method for producing the same which make it possible to allow a juncture portion between display components to be scarcely conspicuous when a large screen display device is produced by arranging the plurality of display components.
Another object of the present invention is to provide a display device excellent in repair performance and a method for producing the same which make it possible to easily exchange a disabled display component with new one, in addition to the requirement described above.
Still another object of the present invention is to provide a display device and a method for producing the same which make it possible to assemble the display device at a working site and effectively reduce the production cost.
According to the present invention, there is provided a display device comprising a main display device body including two or more display components arranged on a first principal surface of an optical guide plate for introducing light from a light source thereinto, wherein a substance having a light-transmitting property adjusted for its refractive index is allowed to intervene at least between the optical guide plate and the display components.
In this arrangement, the main display device body can be easily produced by arranging the display components along the first principal surface, while a display surface of the display component is opposed to the first principal surface of the optical guide plate for introducing the light from the light source thereinto, and the substance having the light-transmitting property adjusted for its refractive index is allowed to intervene between the surfaces.
According to another aspect of the present invention, there is provided a display device comprising a main display device body including two or more display modules arranged on a first principal surface of an optical guide plate for introducing light from a light source thereinto, wherein a substance having a light-transmitting property adjusted for its refractive index is allowed to intervene at least between the optical guide plate and the display modules.
In this arrangement, the main display device body can be easily produced by arranging the display modules along the first principal surface, while a display surface of the display module is opposed to the first principal surface of the optical guide plate for introducing the light from the light source thereinto, and the substance having the light-transmitting property adjusted for its refractive index is allowed to intervene between the surfaces.
The display module can be easily produced by arranging the display components along a first principal surface of a module optical guide plate, while a display surface of the display component is opposed to the first principal surface of the module optical guide plate for introducing the light from the light source thereinto, and a second substance having a light-transmitting property adjusted for its refractive index is allowed to intervene between the surfaces.
In the display device of the present invention described above, when the refractive index of the substance is adjusted to be substantially the same as the refractive index of the optical guide plate, it is possible to obtain a large screen display device in which the juncture portion of the display components or the display modules is scarcely conspicuous when the large screen display device is produced by arranging the plurality of display components or the plurality of display modules are arranged to produce the large screen display device.
The display module may be constructed by arranging two or more display components on a first principal surface of a module optical waveguide plate for introducing the light from the light source thereinto, and a second substance having a light-transmitting property adjusted for its refractive index is allowed to intervene at least between the module optical waveguide plate and the display components.
In the display device according to the present invention, it is preferable to use a display component described, for example, especially in Japanese Laid-Open Patent Publication Nos. 10-78549 and 11-194723. That is, the display component described in these patent documents comprises an optical waveguide plate for introducing light from a light source thereinto, a ceramic substrate provided opposingly to a back surface of the optical waveguide plate, and a large number of picture element assemblies arranged between the optical waveguide plate and the ceramic substrate. Any warpage occurs in the ceramic substrate in some cases due to the shrinkage phenomenon during the sintering. Any warpage also occurs in the entire display component resulting therefrom in some cases.
However, in the display device according to the present invention, when an adhesive is used as the substance or the second substance having the light-transmitting property adjusted for its refractive index, the display component is consequently secured with the adhesive to the optical guide plate or the module optical waveguide plate. Therefore, for example, the entire first principal surface (display surface) of the optical waveguide plate of each of the display components is secured to the optical guide plate with the adhesive intervening therebetween. At this stage, the warpage, which has occurred in the display component, is absorbed by the adhesive. Thus, the display component is tightly secured to the optical guide plate.
It is also preferable that the optical guide plate includes a plurality of divided optical guide plates which are arranged in a matrix configuration, and the plurality of divided optical guide plates are secured to one another with an adhesive having a light-transmitting property adjusted for its refractive index.
The substance having the light-transmitting property adjusted for its refractive index will now be explained. At first, as for the refractive index of the substance, it is preferable that the difference between the refractive index of the optical guide plate and the refractive index of the substance is decreased to be as small as possible, in order to avoid any sense of incongruity at the juncture of the display components or the display modules or at the juncture of the divided optical guide plates. The allowable difference in refractive index also relates to the thickness of the optical guide plate. However, assuming that the refractive index of the optical guide plate is N1, the sense of incongruity can be generally avoided at the juncture if the refractive index N2 of the substance satisfies the following expression:
0.9N1xe2x89xa6N2xe2x89xa61.1N1
In addition to the effect described above, the thickness of the optical guide plate can be increased, and the assembling performance and the stability of the structure after the assembling are improved, if the refractive index N2 of the substance satisfies the following expression:
0.99N1xe2x89xa6N2xe2x89xa61.01N1
On the other hand, the juncture of the display components or the display modules or the juncture of the divided optical guide plates involves such a structural problem that the display components or the display modules are arranged. For this reason, the pitch of the picture element ranging over the juncture is larger than the ordinary pitch of the picture element, and the juncture is conspicuous in many cases. Accordingly, the refractive index is preferably adjusted to satisfy the following expression:
N1 less than N2xe2x89xa61.01N1
Accordingly, when the light emitted from the picture element passes through the juncture portion, the light is refracted in accordance with the relationship of the refractive indexes adjusted as described above. At the stage at which the light outgoes from the display surface, the pitch of the picture element ranging over the juncture consequently approaches the ordinary pitch of the picture element. Thus, it is possible to mitigate the sense of incongruity at the juncture.
The light-transmitting property of the substance is preferably determined in order that the light is successfully introduced up to the display component in an efficient manner, and the electric power consumption is suppressed. That is, it is preferable that the transmittance is not less than 50% for the incident light at the right angle at the wavelength in the visible light region. It is more preferable that the transmittance is not less than 70%.
The form of the substance may be any one of gas, liquid, and solid, or it may be a mixture thereof, provided that the substance satisfies the foregoing conditions.
The shape of the divided optical guide plate may be any one including, for example, rectangular parallelepiped, prism, column, and truncated pyramid, provided that the display component or the display module can be secured thereto, and the display component or the display module can be stacked in a stable manner. However, the shape is preferably rectangular parallelepiped in view of the machining performance and the assembling performance.
In view of the assembling performance and the repair performance, the size of the divided optical guide plate is preferably a size having a length of 40 mm to 500 mm and a width of 40 mm to 500 mm. The thickness is preferably 2 mm to 40 mm in order to satisfy both of the assembling performance and the disappearance of the sense of incongruity at the juncture.
The material for the optical guide plate, the divided optical guide plate, or the module optical waveguide plate may be either an inorganic material or an organic material, provided that the light-transmitting property is satisfactory at the wavelength in the visible light region. Specifically, it is possible to use a simple substance or a combined material composed of, for example, glass, quartz, light-transmitting alumina, acrylic resin, methacrylic resin, polycarbonate, vinyl chloride resin, phenol resin, vinyl acetate resin, ABS, fluororesin, and unsaturated polyester resin. Especially, in view of the cost and the machining performance, it is preferable to use glass, acrylic resin, and methacrylic resin. As for the glass, it is preferable to use, for example, Vycor glass, 96% silicate glass, alumino silicate glass, borosilicate glass, zinc borosilicate glass, and barium borosilicate glass. As for the light-transmitting property, it is preferable that the transmittance is not less than 50% for the perpendicular incident light at the wavelength in the visible light region. It is more preferable that the transmittance is not less than 70%.
Explanation will now be made for the adhesive for securing the display component to the module optical waveguide plate and the adhesive as the substance, or the adhesive for securing the divided optical guide plates to one another. The adhesive herein has the meaning including adhesive, glue or sticker, adhesive to be solidified after curing, adhesive to be flexible after curing, rubber-like adhesive, and gel-like adhesive.
The curing method is not specifically limited, including, for example, those of the types of UV setting, hot setting, cold setting, condensation setting, addition setting, and two-part setting.
The material may be either an inorganic material or an organic material, provided that the light-transmitting property is satisfactory at the wavelength in the visible light region. It is preferable to use those which have high insulating performance and low ignitability. It is more preferable to use those which are excellent in wettability with respect to the optical guide plate and which are stable for a long period of time, for example, against heat, light, and moisture.
Specifically, it is possible to use a simple substance or a combined material based on, for example, urea-formaldehyde resin, phenol resin, epoxy resin, acrylic resin, methacrylic resin, cyanoacrylate, polyurethane, emulsion, hot melt, synthetic rubber, and natural rubber.
Especially, as for the adhesive for securing the display component to the module optical waveguide plate, it is preferable to use the adhesive to be solidified after curing, in order to avoid any securing discrepancy of the display component. In order to mitigate the thermal expansion, it is preferable to use the adhesive to be flexible after curing and the rubber-like adhesive. As for the adhesive as the substance having the light-transmitting property adjusted for its refractive index, it is preferable to use the adhesive to be flexible after curing, the rubber-like adhesive, and the gel-like adhesive, in order to effect the mitigation of the thermal expansion and the detachment performance upon repair.
In other words, when those to be completely solidified are used as the adhesive, the respective display components and the respective display modules are tightly secured with the adhesive. Therefore, it is possible to obtain the large screen display device having high mechanical strength. However, it is difficult to exchange any disabled display component or any disabled display module with new one. Therefore, such an adhesive is preferably adopted to the large screen display device which assumes the collective exchange all at once.
When those having flexibility are used as the adhesive, then it is possible to obtain the large screen display device having high mechanical strength, and it is easy to perform cutting. Therefore, it is easy to exchange any disabled display component or any disabled display module with new one. Therefore, such an adhesive is excellent in the repair performance. Further, such an adhesive is effective to mitigate the thermal stress generated by the thermal expansion.
It is preferable that the surface of the optical guide plate, the module optical waveguide plate, or the divided optical guide plate is coated with a hard coating material. Accordingly, it is possible to avoid any scratch on the surface of each of the optical guide plates. For example, it is possible to previously avoid such a phenomenon that the white dot locally appears when the black is displayed, or the brightness is increased as a whole.
The coating of the hard coating material referred to herein means the formation of a film or coating of a material having a hardness higher than that of the material for the optical guide plate on the surface of the optical guide plate. The coating on the front and back surfaces of the optical guide plate is important to avoid the scratch. However, it is not necessarily indispensable to apply the coating to the end surfaces. Specifically, those usable as the hard coating material include, for example, acrylic hard coating materials and silicone hard coating materials.
It is preferable that the end surface of the module optical waveguide plate or the divided optical guide plate is mirror-finished. Accordingly, it is possible to lower, up to the level of no sense of incongruity, the leakage of light from the juncture between the module optical waveguide plates or the divided optical guide plates. Thus, the juncture is scarcely conspicuous. Further, it is also possible to ensure a desired angle of visibility. In the mirror-finishing, in order to avoid any sense of incongruity at the juncture, it is preferable that Rmax is not more than 0.3, and it is more preferable that Rmax is not more than 0.05.
Further, it is preferable that when the module optical waveguide plate or the divided optical guide plate is machined, then the dimensional accuracy of the module optical waveguide plate or the divided optical guide plate is not more than xc2x10.1 mm with respect to the reference dimension of 100 mm, the perpendicularity between the end surfaces and between the end surface and the flat surface is not more than 0.1 mm, and the parallelism between the end surfaces and between the flat surfaces is not more than 0.1 mm. It is more preferable that the dimensional accuracy of the module optical waveguide plate or the divided optical guide plate is not more than xc2x10.03 mm with respect to the reference dimension of 100 mm, the perpendicularity between the end surfaces and between the end surface and the flat surface is not more than 0.03 mm, and the parallelism between the end surfaces and between the flat surfaces is not more than 0.03 mm.
Accordingly, it is possible to decrease the cumulative pitch error of the module optical waveguide plate or the divided optical guide plate during the assembling. As a result, it is possible to reduce the distortion of the image which would be otherwise caused by the discrepancy of the pitch of the picture element. It is possible to decrease the gap dispersion of the juncture, and it is possible to make the juncture to be more inconspicuous.
Alternatively, the substance having the light-transmitting property adjusted for its refractive index may be matching oil. In this arrangement, the obtained mechanical strength is not equivalent to that obtained by the adhesive. However, it is easy to exchange the disabled display component or the disabled display module with new one. Therefore, this arrangement is advantageous in repair performance.
In this arrangement, the matching oil is in a form of liquid or grease. The matching oil may be made of either an inorganic material or an organic material, provided that the light transmittance is satisfactory at the wavelength in the visible light region. It is preferable to use those which have high insulating performance and low ignitability. It is more preferable to use those which are excellent in wettability with respect to the optical guide plate and which are stable for a long period of time, for example, against heat, light, and moisture. Specifically, the matching oil includes, for example, dimethyl silicone oil, methyl phenyl silicone oil, glycerol, di-2-ethylhexyl phthalate, silicone grease, and optical gel.
When the matching oil in a liquid form is used, it is preferable that the viscosity is 100 to 1000 cSt, in order to simultaneously satisfy the two factors, i.e., the bubble generated upon application is easily released, and the liquid neither flow nor trickle excessively.
In the present invention, when the plurality of divided optical guide plates are arranged in the matrix configuration, it is also preferable that vertically ruled and/or horizontally ruled support members are allowed to intervene between at least two of the divided optical guide plates. In this arrangement, it is possible to adopt a method in which the vertically ruled and/or horizontally ruled support members are installed before the plurality of divided optical guide plates are arranged in the matrix configuration, and the support members are arranged so that they are interposed between at least two of the divided optical guide plates to produce the large screen display device.
Accordingly, it is possible to cancel the cumulative pitch error which would be otherwise caused during the process of stacking the divided optical guide plates, owing to the presence of the support members. Further, it is possible to absorb the dimensional dispersion of each of the divided optical guide plates. As a result, it is possible to reduce the distortion of the image which would be otherwise caused by the discrepancy of the pitch of the picture element. It is possible to decrease the gap dispersion of the juncture, and it is possible to make the juncture to be more inconspicuous.
In this arrangement, it is preferable that at least the surface of the support member, to which the end surface of the divided optical guide plate is opposed, is mirror-finished. Accordingly, it is possible to make the juncture to be inconspicuous, and it is possible to ensure the angle of visibility.
It is also preferable that the support member is formed to have a lattice-shaped configuration. In this arrangement, it is possible to tightly hold the divided optical guide plates. Further, it is possible to eliminate the cumulative pitch error in the vertical direction and in the horizontal direction. Furthermore, it is extremely easy to stack the divided optical guide plates, and it is possible to reduce the number of steps.
The support member may be made of either an inorganic material or an organic material, provided that the light-transmitting property is satisfactory at the wavelength in the visible light region. Specifically, it is possible to use a simple substance or a combined material composed of, for example, glass, quartz, light-transmitting alumina, acrylic resin, methacrylic resin, polycarbonate, vinyl chloride resin, phenol resin, vinyl acetate resin, ABS, fluororesin, and unsaturated polyester resin.
The support member is preferably made of the same material as that for the optical guide plate of the divided optical guide plate, for example, in view of the fact that the refractive index is identical, and the coefficient of thermal expansion is identical. As for the light-transmitting property, it is preferable that the transmittance is not less than 50% for the perpendicular incident light at the wavelength in the visible light region. It is more preferable that the transmittance is not less than 70%. The thickness of the support member is preferably 0.5 to 10 mm in order that there is no sense of incongruity at the juncture, and the support member has rigidity as a structural member.
It is also preferable that the display device of the present invention further comprises another optical guide plate arranged for a display surface of the main display device body, wherein a substance having a light-transmitting property adjusted for its refractive index is allowed to exist between the display surface and the another optical guide plate. Those usable as the another optical guide plate may have a structure composed of a transparent vessel filled with the substance having the light-transmitting property adjusted for its refractive index at the inside.
This arrangement is advantageous in that the juncture of the display components or the display modules is inconspicuous. Further, the assembling performance is satisfactory. Especially, when the matching oil is used as the substance having the light-transmitting property adjusted for its refractive index, the repair performance is also satisfactory. In this case, it is preferable to allow a seal member to intervene between the matching oil and the atmospheric air.
The seal member includes adhesive, glue or sticker, adhesive to be solidified after curing, adhesive to be flexible after curing, rubber-like adhesive, and gel-like adhesive. Alternatively, the seal member may be obtained by depositing such a material on a film-shaped member.
The material may be either an inorganic material or an organic material. It is preferable to use a material which does not cause any reaction with a substance to make contact therewith. Specifically, for example, it is possible to use those based on silicone, modified silicone, polysulfide, polyurethane, acrylic, epoxy, SBR, and butyl rubber.
It is preferable that the end of the seal member, which contacts with the atmospheric air, is subjected to surface adjustment with respect to (flushed with) the plane of the optical guide plate, in order that the light traveling in the optical guide plate is reflected at an appropriate angle. When a light-absorbing material is applied to the end, the light, which incomes at an unsuitable angle, can be absorbed. Therefore, it is possible to improve the image quality. In this case, it is unnecessary to make the surface adjustment for the end with respect to the optical guide plate. Accordingly, the degree of freedom of design is increased. Those usable as the light-absorbing material include, for example, pigments and dyes.
The another optical guide plate may be manufactured such that a plurality of divided optical guide plates are arranged in a matrix configuration, and they are secured to one another with an adhesive having a light-transmitting property adjusted for its refractive index.
The another optical guide plate may be made of either an inorganic material or an organic material, provided that the light-transmitting property is satisfactory at the wavelength in the visible light region. Specifically, it is possible to use a simple substance or a combined material composed of, for example, glass, quartz, light-transmitting alumina, acrylic resin, methacrylic resin, polycarbonate, vinyl chloride resin, phenol resin, vinyl acetate resin, ABS, fluororesin, and unsaturated polyester resin.
The another optical guide plate is preferably made of the same material as that for the optical guide plate of the main display device body, for example, in view of the fact that the refractive index is identical, and the coefficient of thermal expansion is identical. As for the light-transmitting property, it is preferable that the transmittance is not less than 50% for the perpendicular incident light at the wavelength in the visible light region. It is more preferable that the transmittance is not less than 70%. The thickness of the another optical guide plate is preferably 0.5 to 10 mm in view of the assembling performance.
When the optical guide plate of the main display device body is constructed by arranging the plurality of divided optical guide plates, it is not necessarily indispensable that the substance having the light-transmitting property adjusted for its refractive index (conveniently referred to as xe2x80x9cfirst substancexe2x80x9d), which is allowed to exist between the display surface of the main display device body and the another optical guide plate, is identical with the substance having the light-transmitting property adjusted for its refractive index (conveniently referred to as xe2x80x9csecond substancexe2x80x9d) which is allowed to exist at the end surface portion of the divided optical guide plate.
When the first and second substances are composed of different materials, it is preferable that the refractive index N3 of the first substance satisfies the following expression, provided that the refractive index of the optical guide plate of the main display device body is N1, and the refractive index of the another optical guide plate is N2:
0.9N1xe2x89xa6N3xe2x89xa61.1N2(N1xe2x89xa6N2)
or
0.9N2xe2x89xa6N3xe2x89xa61.1N1(N2xe2x89xa6N1)
Accordingly, the light can be sufficiently introduced into the display component, and it is possible to ensure the display brightness of the screen. In order to efficiently introduce the light into the display component and suppress the electric power consumption, it is preferable that the transmittance is not less than 50% for the perpendicular incident light at the wavelength in the visible light region. It is more preferable that the transmittance is not less than 70%.
When the first and second substances are composed of mutually different materials, and when the both are liquid, it is possible to prevent them from being mixed with each other by allowing a seal member to intervene between the both. When at least any one of them is solid or when both of them are solid, they are not mixed with each other. Therefore, it is possible to omit the installation of the seal member. When the foregoing conditions are satisfied, the first and second substances may be in any form including gas, liquid, and solid, or they may be a mixture thereof.
In the present invention, it is also preferable that the main display device body is accommodated in a vessel with its at least one surface having transparency; and a substance having a light-transmitting property adjusted for its refractive index is allowed to exist between a display surface of the main display device body and the surface of the vessel having the transparency.
In this arrangement, it is possible to adopt a method in which the main display device body is accommodated in the vessel, and the vessel is filled therein with the substance having the light-transmitting property adjusted for its refractive index to produce the large screen display device.
The surface having the transparency, of the surfaces for constructing the vessel may be made of either an inorganic material or an organic material, provided that the light-transmitting property is satisfactory at the wavelength in the visible light region. Specifically, it is possible to use a simple substance or a combined material composed of, for example, glass, quartz, light-transmitting alumina, acrylic resin, methacrylic resin, polycarbonate, vinyl chloride resin, phenol resin, vinyl acetate resin, ABS, fluororesin, and unsaturated polyester resin.
The surface of the vessel is preferably made of the same material as that for the optical guide plate of the main display device body, for example, in view of the fact that the refractive index is identical, and the coefficient of thermal expansion is identical. As for the light-transmitting property, it is preferable that the transmittance is not less than 50% for the perpendicular incident light at the wavelength in the visible light region. It is more preferable that the transmittance is not less than 70%. The thickness of the surface is preferably 0.5 to 100 mm in view of the assembling performance.
It is also possible to adopt a method comprising allowing a display surface of the main display device body to be opposed to a first principal surface of a plate member having transparency, and allowing a substance having a light-transmitting property adjusted for its refractive index to intervene between the surfaces, wherein the main display device body is fixed, and then a vessel including a constitutive component of the plate member is produced, so that the vessel is filled therein with the substance having the light-transmitting property adjusted for its refractive index to produce a large screen display device.
When matching oil is used as the substance having the light-transmitting property adjusted for its refractive index, it is necessary to allow a seal member to intervene between the substance and the atmospheric air. However, in the arrangement described above, the main display device body is consequently accommodated in the vessel filled with the matching oil. Therefore, it is unnecessary to use the seal member. This arrangement is also advantageous in that the juncture between the display components or between the display modules is inconspicuous. Further, the assembling performance is satisfactory, and the repair performance is satisfactory as well.
It is also preferable to use, as the plate member having the transparency, a member obtained by arranging a plurality of divided plates in a matrix configuration, and securing them to one another with an adhesive having a light-transmitting property adjusted for its refractive index. In this arrangement, it is possible to use the plate member which is compact and inexpensive. Further, it is possible to use the plate member having a good quality having few defects such as bubbles and foreign matters at the inside.
The arrangement described above may be exemplarily modified as follows. That is, a substance, which is different from the substance having the light-transmitting property adjusted for its refractive index, is allowed to exist between the vessel and the surface of the main display device body disposed oppositely to the display surface. In this arrangement, it is possible to adopt a method comprising allowing a display surface of the main display device body to be opposed to a first principal surface of a plate member having transparency, and allowing a substance having a light-transmitting property adjusted for its refractive index to intervene between the surfaces, wherein the main display device body is fixed, and then a vessel including a constitutive component of the plate member is produced, so that the vessel is filled therein with another substance which is different from the substance having the light-transmitting property adjusted for its refractive index to produce the display device.
In the case of this arrangement, when the substance having the light-transmitting property adjusted for its refractive index is matching oil, it is preferable to allow a seal member to intervene between the matching oil and the another substance. In the case of the arrangement described above, the substance having the light-transmitting property adjusted for its refractive index tends to be expensive. However, it is possible to decrease the range of the use of the substance. Therefore, this arrangement is advantageous to reduce the production cost, and it is advantageous in that no bubble is generated in the substance having the light-transmitting property adjusted for its refractive index.
The another substance and the substance having the light-transmitting property such as the matching oil to be charged in the vessel are preferably in the form of liquid or grease. The driving circuit of the main display device body is also immersed in the substances. Therefore, it is preferable to use those which have high insulating performance and low ignitability. When the another substance has a specific gravity which is equivalent to that of the substance having the light-transmitting property adjusted for its refractive index, the pressure, which is exerted on the main display device, is uniform without being affected by the depth, which is preferred.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example.